Switch mechanism



Feb. 18, 1930. w. H. SCHRAMM 1,747,491

SWITCH MECHANISM 2 Sheets-Sheet 2 Filed May 26, 1927 F175. 2. I w

Fig. 3.

\ ri' i INVENTOR WaizerH. Schmmm.

Patented Feb. 18, 1930 warren srres WALTER H. SGHRAMM, OF PITTSBURGH,PENNSYLVANIA, ASSIG'NOB TO WESTING- HOUSE ELECTRIC & MANUFACTURINGCOMPANY, A CORPORATION OF PENNSYL- VANIA SWITCH MECHANISM Applicationfiled May 26,

My invention relates to switch mechanism and particularly todisconnecting switches of the back-of-board type, wherein an insulatingpanel is mounted at the rear of a sheet metal switchboard and serves tosupport fuses and knife switches having an operating handle projectingthrough an opening in the switchboard.

An object of my invention is to provide a back-of-board knife switchthat is assembled entirely upon an insulating base and mounted at therear of the switchboard and having an operating handle that is alsomounted upon the insulating panel in order that the switch may beassembled upon the insulating base as a unit, thereby facilitatingassembly and inspection of the switch apparatus.

Another object of my invention is to provide a back-of-board typedisconnecting switch having characteristics of design which enables themounting of the insulating panel supporting switch, closer to theswitchboard than is the usual custom, thus reducing the distance of thefuse receptacles mounted on the insulating base, from the front of theboard, and thereby rendering its operation more safe, because it isunnecessary for the operator to reach into a deep and dark recess toreplace a fuse.

Another object of my invention is to provide a back-of-board type knifeswitch wherein the over-all dimensions of the switch blade assembly areshortened, in order to reduce the space necessary for the safe operationof the switch.

A further object of my invention is to provide a back-of-board typedisconnecting switch having the above-noted characteristics that isinexpensive to manufacture, and which may readily be assembled andinstalled upon the usual type of metal front switchboards.

These and other objects of my invention, that will be made apparentthroughout the further description thereof, are attained by means of theswitch apparatus hereinafter described and illustrated in theaccompanying drawings, wherein:

Figure 1 is an elevational View of switch apparatus embodying featuresof my inven- 1927. Serial No. 194,248.

tion showing the metal front switchboard in section.

Fig. 2 is a plan view of the apparatus shown in Figure l with the coverremoved to expose parts of the apparatus, and

Fig. 3 is an elevational view of a fragment of the switch apparatus withthe insulating panel shown in section.

Referring to the drawings, the switch apparatus includes a sheet metalswitchboard at, and an insulating base or panel 5 that is attached tothe switchboard f by brackets 6. Contact jaws 7 and pivot jaws 8 aremounted upon the panel 5, the pivot jaw 8, )ivotally supporting a knifeswitch blade 9 that engages the contact jaw 7. Fuse receptacles or clips11 are mounted upon the panel 5 for supporting standard cartridge fuses12. The pivot jaws 8 and the adjacent fuse clip 11 are electricallyconnected by the conductor strap 13 that is secured to the insulatingpanel by screws 14.

A three-pole knife switch is illustrated in Fig. 2. Fig. l is a typicalside elevation of a 2 or 4 pole switch. A pedestal 15 is mounted uponthe central conductor or strap 13 he tween the contact jaw 8 and thefuse clip 11 on 1 or 3 pole switches, as shown in Fig. 3.

The pedestal is adapted to support the switch operating handle, to behereinafter described, and comprises a square shaft 16 having one endextending through the panel 5 and threaded to receive nut 17 forattaching the shaft to the panel. The shaft is provided with a shouldercollar 18 which engages an insulating bushing 19 that is disposec between the collar 18 and the base 5 on 2 or l pole switches, or theconductive strap 13 for 1 and 3 pole switches. The threaded end of theshaft 16 is insulated from the strap 13 by an insulating bushing 21which extends through an opening 22 in the strap 13. The bushing 21extends into the bore 23 of the bushing 19.

By reason of the relatively wide diameter of the insulating bushing 19,the pedestal 15 is provided with a wide supporting base and therefore isrigidly mounted upon the base 5.

The operating handle 26 for the switch mechanism comprises a single bentstrap 27,

of U-shape, that is disposed on opposite sides of the shaft 16 in spacedrelation thereto, the bars being pivotally mounted upon the shaft 28adjacent the center of the bars. Interlocking cams 29, the purpose ofwhich will hereinafter appear, are mounted in the spaces between straps27 of the operating handle and on the shaft 16, the cams being securedin place by rivets-30.-

Each switch blade 9 is provided with an insulating clip 31 that issecured thereto by rivets The clips are connected for simultaneousoperation by means of a metal shaft 33 that extends through holes 34, inthe ends of the clips. Longitudinal displacement of the shaft isprevented by cotter to a pivoted operating handle upon the front plateof the switchboard. This construction required a greater space betweenthe front plate of the switchboard and the insulating panel, in order toaccommodate the greater length of the switch blade and to provide properclearance for live'parts. Switches'of this character also haddisadvantages the assembly thereof, because the operating mechanism isusually mounted upon the front plate of the switchboard. In my improvedswitch blade apparatus, the entire switch assembly is mounted upon theswitch base and is independent of the cover or front switchboard.

The switchboard 4 is provided with an opening 37' through which thecartridge fuse 12 is accessible. The opening is closed by a door 38 thatis hinged at 39 to the switchboard 4. The operating handle 26 projectsthrough an opening 41 in the switchboard panel a and is provided with aninsulating handle 42. V

The door 38 is interlocked with the switch handle in such manner thatthe door cannot be opened so long as the switch is in open position andthe switch cannot beclosedso long as the door is in open position. Theinterlock mechanism comprises an arcuate cam member 4L0'that is'attachedto'the door 38 by means of a bolt 43. The camis slightly less in widththan the space between the bars 27 of the operating handle and fitswithin that space when inthe closed position shown in full lines inFigures 1 and 2. The cam plates 29 on the operating handle are providedwith arcuate cam surfaces 44 which provide clearance for the cam 40 whenthe operating handle is in the open position shown in dotted lines. Itwill be seen that the door cannot be opened so long as the switch is inthe closed position because the upper end of the cam 40 engages'theconvex surface 39 of the cam 29 and prevents-movement of the door. Theconvex cam surface is of such length that it'prevents'movement of thedoor until the-switchhas'been moved to its full open position. At thistime, cam 40 will clear the cam 29 and permit opening movement of thedoor. However, when the cam a0 has moved to the open position, theswitch cannot be closed because the concave surface 4% of the cam'29will then'engage the convex cam surface of the cam 40'a-nd preventclosing'movement ofthe switch so; long as the door 1s in open positlon.The arrangement of-the cams issuch that in orderto close the switch, thedoor must be in fully closed position.

The switch construction, above described, is relatively compact andrugged and isrendered more safeinoperation by.- reason' of the fact thatthe fuses l-2-are'disposed relatively close to the front switchboard 4:.

It will be understood that theiswitchboard 4 is of theme'tal panel typeand may be as sembled in panels or sections which; may.-

be removed for inspection of the switch mechanism. v

While I have shown and described my invention in considerable detail forthe purpose of completely illustrating the same, it is my intent-ionthat the appended claims shall be as broadly construed asis'permitte'dby the'langu-age thereofand thei prior art.

I c'laiin as my invention:

1. Switch mechanism comprising a'- sup portingbase, a switch blademember pivoted thereon for movement in a plane normal to the plane ofthe base, a pedestal mountedupon the base andextendingperpendicularlytherefrom, and an operating handle comprising aforked member having portions disposed on opposite sides of the pedestaland pivoted thereto inter-mediate their ends, the inner ends of the saidportions being pivotally connected to the said switch menr ber.

2. Switch mechanism comprising a supporting base, a plurality of switchblade that the links may move past the pedestal when their operatinghandle is actuated.

3. Switch mechanism comprising a supporting base, a switch blade memberpivoted

